A strontium carbonate powder is of value as a material for producing dielectric material powders such as strontium titanate powder. For instance, the strontium titanate powder can be produced by mixing strontium carbonate powder and titanium dioxide powder to give a mixture thereof and calcinating the mixture. The dielectric material powders can be utilized for producing dielectric ceramic layers of multilayer ceramic capacitors.
Since electronic devices are recently requested to have a smaller size, the multilayer ceramic capacitors are also requested to have a smaller size. In order to manufacture multilayer ceramic capacitors, it is required that the dielectric ceramic layers of multilayer ceramic capacitors have a decreased thickness. In order to produce dielectric ceramic layers having a decreased thickness, it is necessary to employ fine dielectric ceramic powders having a uniform composition.
The fine and uniform dielectric ceramic powders can be produced from a uniform powdery mixture comprising fine ceramic components. The uniform powdery mixture is generally produced by a wet-mixing procedure. Therefore, it is desirous that the strontium carbonate powder for the production of a dielectric ceramic powder is fine and shows high dispersiblity in liquid media.
JP 2007-76934 A discloses a process for preparing a fine strontium carbonate powder, which comprises the steps of supplying gaseous carbonate dioxide into an aqueous solution or dispersion containing strontium hydroxide in an amount of 1 to 20 wt. % under stirring at a flow rate of 0.5 to 200 mL/min., per one gram of the strontium hydroxide, in the presence of an organic acid having 3 to 12 carbon atoms and at least two carboxyl groups or hydroxyl groups or carboxyl group in one molecule, thereby carbonating the strontium hydroxide to give an aqueous dispersion containing strontium carbonate particles; and drying the dispersion. Examples of the organic acid include citric acid, malic acid, adipic acid, gluconic acid, glucaric acid, tartaric acid, maleic acid, and ascorbic acid. Preferred are citric acid and ascorbic acid. JP 2007-76934 further describes that the disclosed process gives a fine strontium carbonate powder having a specific surface of 52 to 300 m2/g and that the fine strontium carbonate powder can be pulverized by means of ceramic beads to give strontium carbonate particles comprising primary particles having a size of 5 to 50 nm (size calculated from projected area thereof) and an aspect ratio of 2 or less.
JP 2008-222496 A discloses that a fine strontium carbonate powder showing increased dispersibility in liquid media can be prepared by treating a strontium carbonate powder with a polymer comprising a polycarboxylic acid or anhydride thereof which has a side chain of polyoxyalkylene group. JP 2008-222496 A further discloses that the treatment of a strontium carbonate powder with a polymer comprising a polycarboxylic acid or anhydride thereof which has a side chain of polyoxyalkylene group can be performed by pulverizing strontium carbonate particles in an aqueous medium containing the polymer by the use of ceramic beads.